A robot is located at the top-left corner of a m x n grid (marked ‘Start’ in the diagram below). The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked ‘Finish’ in the diagram below). How many possible unique paths are there?…… Continue reading Leetcode Unique Paths Java Solution
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Leetcode Sum Root to Leaf Numbers Java Solution
Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number. An example is the root-to-leaf path 1->2->3 which represents the number 123. Find the total sum of all root-to-leaf numbers. Note: A leaf is a node with no children. Example: Input: [1,2,3] 1 / \ 2 3 Output: 25 Explanation: The root-to-leaf path 1->2 represents…… Continue reading Leetcode Sum Root to Leaf Numbers Java Solution
Leetcode 787 Cheapest Flights Within K Stops Java Solution
There are n cities connected by m flights. Each flight starts from city u and arrives at v with a price w. Now given all the cities and flights, together with starting city src and the destination dst, your task is to find the cheapest price from src to dst with up to k stops. If there is no…… Continue reading Leetcode 787 Cheapest Flights Within K Stops Java Solution
Leetcode 200 Number of Islands (Java) With Video Explanation
Given a 2d grid map of ‘1’s (land) and ‘0’s (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by water. Example : Input: 11000 11000 00100 00011 Output: 3 Solution: We…… Continue reading Leetcode 200 Number of Islands (Java) With Video Explanation
Leetcode 56 Merge Intervals (Java)
Given a collection of intervals, merge all overlapping intervals. Example 1: Input: [[1,3],[2,6],[8,10],[15,18]] Output: [[1,6],[8,10],[15,18]] Explanation: Since intervals [1,3] and [2,6] overlaps, merge them into [1,6]. Solution: We can solve this by comparing the start of the next interval with the end of the current interval and merged if the start of the next interval…… Continue reading Leetcode 56 Merge Intervals (Java)